Secondary Parking Apparatus for a Heavy Vehicle

ABSTRACT

A secondary parking apparatus is provided for a vehicle having components of a parking brake system, components of an anti-lock brake system (ABS). and a manually-operable device. The secondary parking apparatus comprises an electronic controller arranged to (i) monitor the manually-operable device to detect an operator intent signal to apply parking brakes of the parking brake system, (ii) receive a combination of one or more signals indicative of a fault condition of the vehicle, and (iii) provide one or more control signals to be applied to components of the ABS to selectively exhaust air pressure from components of the ABS to atmosphere so that parking brakes of the parking brake system are applied to park the vehicle when both the operator intent signal and the combination of one or more signals indicative of a fault condition of the vehicle are detected.

BACKGROUND

The present application relates to heavy vehicle parking, and isparticularly directed to a secondary parking apparatus for a heavyvehicle such as a truck.

Vehicle parking systems for trucks are known. One type of vehicleparking system for trucks is an electronic park system. In someelectronic park systems, electrical lines are used in place of pneumaticlines in the dashboard area of the truck. It would be desirable toprovide a redundant parking mechanism for electronic park systems fortrucks.

SUMMARY

In accordance with one embodiment, a secondary parking apparatus isprovided for a Vehicle having components of a parking brake system,components of an anti-lock brake system (ABS), and a manually-operabledevice for, when operated by a vehicle operator, providing an operatorintent signal indicative of the vehicle operator's intent to applyparking brakes of the parking brake system. The secondary parkingapparatus comprises a first electronic controller arranged to (i)monitor the manually-operable device to detect an operator intentsignal, and (ii) provide one or more parking control signals to beapplied to components of the parking brake system to apply the parkingbrakes when an operator intent signal is detected. The secondary parkingapparatus also comprises a second electronic controller arranged to (i)monitor the manually-operable device to detect an operator intentsignal, (ii) receive a combination of one or more signals indicative ofa fault condition of the vehicle, and (iii) provide one or more controlsignals to be applied to components of the ABS to selectively controlcomponents of the ABS to selectively exhaust air pressure from thecompressed air supply so that parking brakes of the parking brake systemare applied to park the vehicle when both the operator intent signal andthe combination of one or more signals indicative of a fault conditionof the vehicle are detected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram showing a secondary parkingapparatus constructed in accordance with an embodiment.

FIG. 2 is a flow diagram depicting operation of a secondary parkingapparatus in accordance with an embodiment.

FIG. 3 is a schematic block diagram showing a secondary parkingapparatus constructed in accordance with another embodiment.

DETAILED DESCRIPTION

Referring to FIG. 1, secondary parking apparatus 10 is provided for usein a heavy vehicle such as a truck. Secondary parking apparatus 10 isconstructed in accordance with one embodiment. In FIG. 1, electricalline connections are shown as solid lines, and pneumatic linesconnections are shown as dashed lines.

Device 12 is operable by an operator such as a driver of the vehicle.When device 12 is manually operated by the vehicle driver, device 12provides at least one signal on line 14 indicative of the vehicledriver's intent to apply parking brakes of the vehicle. Device 12 maycomprise a switch of an integrated switching module which is mounted ona dashboard of the vehicle. Device 12 may comprise any electrical,pneumatic, or electropneumatic device which can be operated by anoperator such as the vehicle driver.

Parking brake controller 20 monitors signal on line 14 from device 12indicative of the vehicle driver's intent to apply parking brakes of thevehicle. Parking brake controller 20 provides one or more controlsignals on line 22 to control operation of parking brakes of thevehicle. More specifically, parking brake controller 20 provides signalson line 22 to control operation of parking brake valves 30. Compressedair supply 50 provides a source of compressed air in line 52 to parkingbrake valves 30. Parking brake valves 30 are controlled by parking brakecontroller 20 to vary pneumatic pressure in line 32 to one or morechambers of spring brake chambers 40.

When the vehicle driver desires to apply parking brakes of the vehicle,the driver operates device 12. Parking brake controller 20 providessignals on line 22 in response to receiving signal on line 14 indicativeof the driver's intent to apply parking brakes of the vehicle. Signalson line 22 are applied to parking brake valves 30 so as to exhaust airin one or more chambers of spring brake chambers 40 which areoperatively coupled in known manner to parking brake springs 42. Whenair in spring brake chambers 40 is exhausted and/or system air pressuredrops to less than about 45 psi to 60 psi, parking brake springs 42 areautomatically applied without any human intervention to apply thevehicle parking brakes, as is known, Structure and operation of parkingbrake controller 20 and parking brake valves 30 for controllingoperation of spring brake chambers 40 and parking brake springs 42 topark the vehicle are conventional and, therefore, will not be furtherdescribed.

Parking brake controller 20 also applies one or more signals on line 24to electronic air control system 58 which is connected via line 56 tocompressed air supply 50. Parking brake controller 20 provides one ormore signals on line 24 to control a governing device (not shown) forcompressed air supply 50 and/or electronic air control system 58 so thatsystem air pressure does not rebuild until after a fault condition ofthe vehicle and any diagnostic trouble codes are corrected. Structureand operation of electronic air control systems and compressed airsupplies are known and, therefore, will not be described.

Anti-lock braking system (ABS) controller 60 communicates with parkingbrake controller 20 via line 34. ABS controller 60 can also be used intraction or stability control systems. ABS controller 60 applies one ormore signals on line 62 to control operation of service brakes of thevehicle. More specifically, ABS controller 60 provides signals on line62 to control operation of traction valves 70 and signals on line 64 tocontrol operation of ABS modulators 80 in response to one or moresignals from wheel speed sensors (not shown), as is known.

ABS controller 60 also applies one or more signals on line 36 toelectronic air control system 58 and/or to a governing device (notshown) for the compressed air supply 50. Compressed air supply 50provides a source of compressed air in line 54 to traction valves 70.Traction valves 70 are controlled by ABS controller 60 to vary pneumaticpressure in line 72 to one or more ABS modulators 80. ABS controller 60also applies one or more signals on line 64 to ABS modulators 80.

In response to one or more signals on line 72 and one or more signals online 64, ABS modulators 80 are controlled by ABS controller 60 to varypneumatic pressure in line 82 to one or more chambers of service brakechambers 90. Service brake chambers 90 and spring brake chambers 40 maycomprise an all-in-one brake actuator, As an example, the brake actuatormay comprise EverSure™ spring brake available from Bendix SpicerFoundation Brake LLC located Elyria, Ohio. ABS controller 60, tractionvalves 70, and ABS modulators 80 comprise part of a conventional ABSsystem, as is known. Structure and operation of ABS systems to controlservice brakes are known and, therefore, will not be described.

In accordance with one embodiment, ABS controller 60 receives signal online 14 from device 12 indicative of the vehicle driver's intent toapply parking brakes of the vehicle. ABS controller 60 also receives acombination of one or more signals on line 16. The combination of one ormore signals on line 16 is indicative of a fault condition of thevehicle. An example fault condition includes loss of electricalcommunication with parking brake valves 30. Another example faultcondition includes a short or open circuit. anywhere in the parkingcontrol circuit. Still another example fault condition includes loss ofactivation means to parking brake valves 30 such that the valves stopworking. These are example fault conditions, and other fault conditionsare possible.

ABS controller 60 provides signal on line 66 to one or more driveralerting devices 18. Driver alerting devices 18 may include anycombination of audio, visual, and haptic devices, for examples. ABScontroller 60 provides signals on line 62 and line 64 to controloperation of traction valves 72 and ABS modulators 80 and thereby tocontrol operation of parking brake springs 42 to apply the vehicleparking brakes in accordance with a method to be described hereinbelow.

Referring to FIG. 2, flow diagram 200 depicts operation of secondaryparking apparatus 10 of FIG. 1 in accordance with an embodiment. In step202, ABS controller 60 monitors signal on line 14 from device 12. Adetermination is made in step 204 as to whether signal on line 14indicative of the vehicle driver's intent to apply parking brakes of thevehicle is detected. If determination in step 204 is negative (i.e.,there is no indication of the vehicle driver intending to apply parkingbrakes of the vehicle), the process returns to step 202 to continuemonitoring signal on line 14 from switch 12. However, if determinationin step 204 is affirmative (i.e., there is an indication of the vehicledriver intending to apply parking brakes of the vehicle), the processproceeds to step 206.

In step 206, a determination is made as to whether there is acombination of one or more signals on line 16 indicative of a faultcondition of the vehicle. If determination in step 206 is negative(i.e., there is no indication of a fault condition of the vehicle), theprocess returns to step 202 to continue monitoring signal on line 14from switch 12. However, if determination in step 206 is affirmative(i.e. there is an indication of a fault condition of the vehicle), ABScontroller 60 provides one or more signals on line 66 to operate driveralerting devices 18. Thereby, in step 207, the driver is alerted of thefault condition.

In step 208, ABS controller 60 applies one or more signals on line 62and one or more signals on line 64 to control traction valves 70 and ABSmodulators 80 to selectively activate a combination of a number oftraction valves and a number of ABS modulators to rapidly exhaust systemair pressure. By exhausting system air pressure, air in spring brakechambers 40 is rapidly depleted. When air in spring brake chambers 40 isdepleted to less than about 45 psi to 60 psi, parking brake springs 42are automatically applied to park the vehicle without any driverintervention.

As an example, ABS controller 60 may selectively activate a combinationof traction valves and ABS modulators associated with the same axle ofthe vehicle to selectively exhaust air pressure from these components onthis vehicle axle. As another example, ABS controller 60 may selectivelyactivate a combination of at least some traction valves and ABSmodulators associated with one axle and at least some traction valvesand ABS modulators associated with a different vehicle axle.Accordingly, as an example, it is conceivable that an ABS modulatorlocated at one corner of the vehicle and. an ABS modulator located at anopposite corner of the vehicle may be controlled to exhaust air pressuretherefrom at the same time or in a predetermined manner such as in apredetermined sequence.

As an example scenario, if the vehicle driver's foot is not pressing ona brake pedal of the vehicle, all ABS modulators may be activated toexhaust air to atmosphere. However, if the vehicle driver's foot ispressing on the brake pedal, one or more ABS modulators may be activatedin a predetermined sequence to exhaust air to atmosphere (using theopposite side on different axles). By selectively exhausting air toatmosphere from ABS modulators in this manner, the vehicle drivermaintains the ability to operate the vehicle service brakes at the sametime the system air pressure is being exhausted to apply the vehicleparking brakes.

It should be apparent that traction valves 70 and ABS modulators 80 areselectively controlled to exhaust air pressure to atmosphere in a mannerto apply parking brake springs of the vehicle to effectively park thevehicle during the fault condition. More specifically, ABS controller 60provides one or more control signals on line 62 and line 64 toselectively control a combination of one or more of traction valves 70and ABS modulators 80 to selectively exhaust system air pressure toatmosphere in a predetermined manner (such as in a predeterminedsequence) so that parking brake springs 42 are applied to park thevehicle.

Program instructions for enabling ABS controller 60 shown in FIG. 1 toperform operation steps in accordance with flow diagram 200 shown inFIG. 2 may be embedded in memory internal to ABS controller 60.Alternatively, or in addition to, program instructions may be stored inmemory external to ABS controller 60. As an example, programinstructions may be stored in memory internal to a different electroniccontroller of the vehicle. Program instructions may be stored on anytype of program storage media including, but not limited to, externalhard drives, flash drives, and compact discs. Program instructions maybe reprogrammed depending upon features of the particular ABScontroller.

A second embodiment of a secondary parking apparatus is illustrated inFIG. 3. Since the embodiment illustrated in FIG. 3 is generally similarto the embodiment illustrated in FIG. 1, similar numerals are utilizedto designate similar components, the suffix letter “a” being associatedwith the embodiment of FIG. 3 to avoid confusion.

Secondary parking apparatus 10 a comprises single electronic controller100. Single electronic controller 100 controls operation of parkingbrake valves 30 a and spring brake chambers 40 a in response to signalfrom switch 12 a in similar manner that parking brake controller 20controls parking brake valves 30 and spring brake chambers 40 inresponse to signal from switch 12 as described hereinabove in theembodiment of FIG. 1. Single electronic controller 100 controlsoperation of traction valves 70 a, ABS modulators 80 a and thereby theoperation of service brake chambers 90 a, and parking brake springs 42 ain response to signal from device 12 a and the combination of one ormore signals indicative of a fault condition of the vehicle in similarmanner that ABS controller 60 as described hereinabove in the embodimentof FIG. 1.

Single electronic controller 100 controls operation of compressed airsupply 50 a and/or electronic air control system 58 a in similar mannerthat parking brake controller 20 controls compressed air supply 50and/or electronic air control system 58 as described hereinabove in theembodiment of FIG. 1. Single electronic controller 100 controlsoperation of driver alerting devices 18 a in similar manner that ABScontroller 60 controls operation of driver alerting devices 18 asdescribed hereinabove in the embodiment of FIG. 1.

It should be apparent that the above-described operation of the ABSsystem provides a function similar to a driver fanning the brakes, butis quicker and automated in response to detecting a fault condition ofthe vehicle and the vehicle driver's intent to apply parking brakes ofthe vehicle. It should also be apparent that a redundant parkingmechanism is provided for an electronic park system without addition ofpneumatic components or electronic components. Accordingly, a redundantparking mechanism is provided at relatively low cost.

Although the above description describes controlling traction valves 70,70 a to exhaust system air pressure, it is conceivable that one or moreelectropneumatic valves may be located upstream of traction valves 70,70 a and controlled to exhaust system air pressure. It is alsoconceivable that one or more electropneumatic valves may be used inplace of traction valves 70, 70 a and controlled to exhaust system airpressure.

Also, although the above description describes use of one electroniccontroller or use of two different electronic controllers, it isconceivable that any number of electronic controllers may be used.Moreover, it is conceivable that any type of electronic controller maybe used. Suitable electronic controllers for use in vehicles are knownand, therefore, have not been described.

Further, although the above description describes parking brakes beingapplied in response to a vehicle driver operating manually-operabledevice 12, 12 a, it is conceivable that the vehicle parking brakes beapplied in response to another means by which the vehicle driver orfleet operator can send a request to park the vehicle. As an example, itis conceivable that the vehicle parking brakes be applied in response tothe vehicle driver operating a key fob. Moreover, it is conceivable thatthe parking brakes be applied in response to an operator who is otherthan the vehicle driver operating a device which is other than a switchon the vehicle. As an example, it is conceivable that the vehicleparking brakes be applied in response to a remote operator communicatingvia satellite to send a request to park the vehicle.

While the present invention has been illustrated by the description ofexample processes and system components, and while the various processesand components have been described in detail, applicant does not intendto restrict or in any limit the scope of the appended claims to suchdetail. Additional modifications will also readily appear to thoseskilled in the art. The invention in its broadest aspects is thereforenot limited to the specific details, implementations, or illustrativeexamples shown and described. Accordingly, departures may be made fromsuch details without departing from the spirit or scope of applicant'sgeneral inventive concept.

What is claimed is:
 1. A secondary parking apparatus for a vehiclehaving components of a parking brake system, components of an anti-lockbrake system (ABS), and a device for providing an operator intent signalindicative of the operator's intent to apply parking brakes of theparking brake system, the secondary parking apparatus comprising: firstelectronic controller arranged to (i) monitor the manually-operabledevice to detect an operator intent signal, and (ii) provide one or moreparking control signals to be applied to components of the parking brakesystem to apply the parking brakes when an operator intent signal isdetected; and a second electronic controller arranged to (i) monitor themanually-operable device to detect an operator intent signal, (ii)receive a combination of one or more signals indicative of a faultcondition of the vehicle, and (iii) provide one or more control signalsto be applied to components of the ABS to selectively control componentsof the ABS to selectively exhaust air pressure so that parking brakesprings of the parking brake system are applied to park the vehicle whenboth the operator intent signal and the combination of one or moresignals indicative of a fault condition of the vehicle are detected. 2.A secondary parking apparatus according to claim 1, wherein the secondelectronic controller arranged to provide one or more control signals tobe applied to components of the ABS to selectively control components ofthe ABS to selectively exhaust air pressure includes the secondelectronic controller arranged to provide the one or more controlsignals to selectively control the components of the ABS to selectivelyexhaust air pressure from an associated compressed air supply toatmosphere in a predetermined manner so that parking brake springs ofthe parking brake system are applied to park the vehicle.
 3. A secondaryparking apparatus according to claim 2, wherein the second electroniccontroller arranged to provide one or more control signals to be appliedto components of the ABS to selectively control components of the ABS toselectively exhaust air pressure includes the second electroniccontroller arranged to provide the one Or more control signals toselectively control the components of the ABS to selectively exhaust airpressure from an associated compressed air supply to atmosphere in apredetermined manner so that parking brake springs of the parking brakesystem are applied to park the vehicle at the same time the vehicleoperator is pressing on a brake pedal of the vehicle to apply theservice brakes.
 4. A secondary parking apparatus according to claim 2,wherein the second electronic controller arranged to provide the one ormore control signals to selectively control the components of the ABS toselectively exhaust air pressure from components of the ABS toatmosphere in a predetermined manner includes the second electroniccontroller arranged to provide the one or more control signals toselectively control a combination of traction valves and ABS modulatorsof the ABS to exhaust air pressure from components of the ABS toatmosphere in a predetermined sequence.
 5. A secondary parking apparatusaccording to claim 1, wherein the second electronic controller isfurther arranged to provide an alert control signal to be applied to anoperator alert device when both the operator intent signal and thecombination of one or more signals indicative of a fault condition ofthe vehicle are detected.
 6. A secondary parking apparatus according toclaim 1, wherein the second electronic controller is further arranged toprovide a compressor control signal to be applied to an electronic aircontrol system so that the electronic air control system is preventedfrom rebuilding system pressure when both the operator intent signal andthe combination of one or more signals indicative of a fault conditionof the vehicle are detected.
 7. A secondary parking apparatus for avehicle having components of a parking brake system, components of ananti-lock brake system (ABS), and a manually-operable device for, whenoperated by a vehicle operator, providing an operator intent signalindicative of the operator's intent to apply parking brakes of theparking brake system, the secondary parking apparatus comprising: asingle electronic controller arranged to (i) monitor themanually-operable device to detect an operator intent signal, (ii)provide one or more parking control signals to be applied to the parkingbrake system to apply the parking brakes when an operator intent signalis detected, (iii) receive a combination of one or more signalsindicative of a fault condition of the vehicle, and (iv) provide one ormore control signals to be applied to components of the ABS toselectively control components of the ABS to selectively exhaust airpressure from components of the ABS so that parking brake springs of theparking brake system are applied to park the vehicle when both theoperator intent signal and the combination of one or more signalsindicative of a fault condition of the vehicle are detected.
 8. Asecondary parking apparatus according to claim 7, wherein the singleelectronic controller arranged to provide one or more control signals tobe applied to components of the ABS to selectively control components ofthe ABS includes the single electronic controller arranged to providethe one or more control signals to selectively control the components ofthe ABS to selectively exhaust air pressure from components of the ABSto atmosphere in a predetermined manner so that parking brake springs ofthe parking brake system are applied to park the vehicle.
 9. A secondaryparking apparatus according to claim 7, wherein the single electroniccontroller arranged to provide one or more control signals to be appliedto components of the ABS to selectively control components of the ABSincludes the second electronic controller arranged to provide the one ormore control signals to selectively control the components of the ABS toselectively exhaust air pressure from an associated compressed airsupply to atmosphere in a predetermined manner so that. parking brakesprings of the parking brake system are applied to park the vehicle atthe same time the vehicle operator is pressing on a brake pedal of thevehicle.
 10. A secondary parking apparatus according to claim 7, whereinthe single electronic controller arranged to provide the one or morecontrol signals to selectively control the components of the ABS toselectively exhaust air pressure from components of the ABS toatmosphere in a predetermined manner includes the single electroniccontroller arranged to provide the one or more control signals toselectively control a combination of traction valves and ABS modulatorsof the ABS to selectively exhaust air pressure from components of theABS to atmosphere in a predetermined sequence
 11. A secondary parkingapparatus according to claim 7, wherein the single electronic controlleris further arranged to provide an alert control signal to be applied toan operator alert device when both the operator intent signal and thecombination of one or more signals indicative of a fault condition ofthe vehicle are detected.
 12. A secondary parking apparatus according toclaim 7, wherein the single electronic controller is further arranged toprovide a compressor control signal to be applied to an electronic aircontrol system so that the electronic air control system is preventedfrom rebuilding system pressure when both the operator intent signal andthe combination of one or more signals indicative of a fault conditionof the vehicle are detected.
 13. A secondary parking apparatus for avehicle having components of a parking brake system and components of ananti-lock brake system (ABS), the secondary parking apparatuscomprising: means for enabling a vehicle operator to apply parkingbrakes of the parking brake system; and means for selectivelycontrolling operation of components of the ABS so that the parking brakesprings of the parking brake system are applied to park the vehicle whenparking brakes of the parking brake system are applied by an operatorand the applied parking brakes are unable to park the vehicle.
 14. Asecondary parking apparatus according to claim 13, wherein the means forselectively controlling operation of components of the ABS includes atleast one electronic controller arranged to provide one or more controlsignals to selectively control components of the ABS to exhaust airpressure from components of the ABS to atmosphere in a predeterminedmanner so that parking brake springs of the parking brake system areapplied to park the vehicle.
 15. A secondary parking apparatus accordingto claim 14, wherein the at least one electronic controller arranged toprovide one or more control signals to selectively control components ofthe ABS to exhaust air pressure from components of the ABS to atmospherein a predetermined manner includes the at least one electroniccontroller arranged to provide the one or more control signals toselectively control a combination of traction valves and ABS modulatorsof the ABS to exhaust air pressure from components of the ABS toatmosphere in a predetermined sequence when the vehicle operator ispressing on a brake pedal of the vehicle.
 16. A secondary parkingapparatus according to claim 15, wherein the means for enabling avehicle operator to apply parking brakes of the parking brake systemincludes a manually-operable switch for, when operated by a vehicledriver, providing a driver intent signal indicative of the vehicledriver's intent to apply parking brakes of the parking brake system. 17.A secondary parking apparatus according to claim 16, wherein the meansfor selectively controlling operation of components of the ABS includesat least one electronic controller arranged to provide an alert controlsignal to be applied to a driver alert device when parking brakes of theparking brake system are applied by a vehicle driver and the appliedparking brakes are unable to park the vehicle.
 18. A secondary parkingapparatus according to claim 17, wherein the at least one electroniccontroller is further arranged to provide a compressor control signal tobe applied to an electronic air control system so that the electronicair control system is prevented from rebuilding system pressure whenparking brakes of the parking brake system are applied by a vehicledriver and the applied parking brakes are unable to park the vehicle.19. A program storage medium readable by a computer having a memory, themedium tangibly embodying one or more programs of instructionsexecutable by the computer to perform method steps for processingsignals of a vehicle having components of a parking brake system andcomponents of an anti-lock brake system (ABS), the method comprising thesteps of: receiving a first signal indicative of a vehicle operator'sintent to apply parking brakes of the parking brake system; receiving asecond signal indicative of a fault condition of the vehicle; providinga third signal to be applied to the parking brake system to apply theparking brakes in response to the first signal being received; andproviding a fourth signal to be applied to the ABS to selectivelycontrol components of the ABS to selectively exhaust air pressure fromcomponents of the ABS so that parking brakes of the parking brake systemare applied to park the vehicle in response to the second signal beingreceived and the third signal being applied to the parking brake systemto apply the parking brakes.
 20. A program storage medium according toclaim 19, wherein providing a fourth signal to be applied to the ABS toselectively control components of the ABS to selectively exhaust airpressure from components of the ABS includes providing the fourth signalto selectively control components of the ABS to selectively exhaust airpressure from components of the ABS to atmosphere in a predeterminedmanner so that parking brake springs of the parking brake system areapplied to park the vehicle.
 21. A program storage medium according toclaim 19, wherein providing the fourth signal to selectively controlcomponents of the ABS to selectively exhaust air pressure fromcomponents of the ABS to atmosphere in a predetermined manner includesproviding the fourth signal to selectively control a combination oftraction valves and ABS modulators of the ABS to selectively exhaust airpressure from components of the ABS to atmosphere in a predeterminedsequence.
 22. A program storage medium according to claim 19, whereinproviding the fourth signal to selectively control components of the ABSto selectively exhaust air pressure from components of the ABS toatmosphere in a predetermined manner includes providing the fourthsignal to selectively control a combination of traction valves and ABSmodulators of the ABS to selectively exhaust air pressure fromcomponents of the ABS to atmosphere in a predetermined sequence occursat the same time as the vehicle operator is pressing on a brake pedal ofthe vehicle to apply the service brakes
 23. A program storage mediumaccording to claim 19, wherein the method further includes the step of:providing a fifth signal to be applied to an operator alert device inresponse to the fourth signal being applied to the ABS to selectivelycontrol components of the ABS.
 24. A program storage medium according toclaim 19, wherein the method further includes the step of: providing afifth signal to be applied to an electronic air control system so thatthe electronic air control system is prevented from rebuilding systempressure in response to the fourth signal being applied to the ABS.